I am hoping someone can help me with the fuel problem I am having . I have read many posts and still I am a lil confused. Heres My issue. 1988 GTA 5.7 Got in it one morning car fired right up like always ran for a few secs then dies. would not start after that. COuld not hear fuel pump prime amymore so I checked the fuse, and the relay. both seem fine. figured pump just died. Havent had much time to work on it so it has set for a few months. Just recently went out and rechanged battery as It had sat for awhile. On a wild thought I stuck the key in and the pump primed and it fired right up and stayed running. shut it down after awhile and tried to start it again, it stumbled a few times then fried again one the 3rd try. I can back out the next day pump primed a started right up again and ran great. after shutting it off I tried to start it the pump would prime car would start then die in a few secs. 3rd time could not here pump. So I grabbed my pressure gauge and hooked it up truned the key and the pump primed to 40psi. started right up then lost pressure over a few secs. truned key off, again pumped primed to 40psi , started then lost pressuer again. on the third try fuel pump was silent again. Im running out of ideas, and before getting into the whole changing of the pump I was hoping someone else might have a good Idea. Thanks for any help in advance

 

Here's the circuit:



Remember that the pump relay will close for two seconds only on ignition power-up. It will not operate again until the ignition has been turned off for at least 20 seconds.

The relay will also operate any time the ECM is receiving distributor reference pulses. If you diagnose the circuit with a voltmeter, you may be able to determine if the relay is operating, whether it is operating at the proper time, or if the pump is receiving voltage or not.

 

Vader,
Please clarify.
The fuel pump relay and oil pressure switch are in parallel, once the engine is running and there's proper oil pressure and the switch is closed does it really matter if the relay is energized, or not?

 

Theoretically, once the engine is running, the relay can fail and the fuel pump will still operate normally. That's if everything is working normally. Obviously, something is not.

I simply wanted to verify power from the relay to the harness before progressing toward the pump. That might indicate that the fuse and connections are good, and that the ECM output and relay circuit are good. If the ECM and relay circuit are operating normally, the pump should run a prime cycle or operate under the conditions described above.

If the relay is not operating, there is obviously something more than just the pump failing.